diff --git a/complex2.cpp b/complex2.cpp
index 697cd48b..08da1681 100644
--- a/complex2.cpp
+++ b/complex2.cpp
@@ -224,7 +224,7 @@ EX namespace westwall {
   void build(vector<cell*>& whirlline, int d) {
     again: 
     cell *at = whirlline[isize(whirlline)-1];
-    cell *prev = whirlline[isize(whirlline)-2];
+    cell *prev = isize(whirlline) >= 2 ? whirlline[isize(whirlline)-2] : NULL;
     if(looped(whirlline)) return;
     for(int i=0; i<at->type; i++) 
       if(at->move(i) && coastvalEdge1(at->move(i)) == d && at->move(i) != prev) {
diff --git a/graph-player.cpp b/graph-player.cpp
index 32ea8a9b..55911e57 100644
--- a/graph-player.cpp
+++ b/graph-player.cpp
@@ -111,7 +111,11 @@ EX void drawWinter(const shiftmatrix& V, ld hdir, color_t col) {
   float ds = ptick(300);
   col = darkena(col, 0, 0xFF);
   for(int u=0; u<20; u++) {
-    ld rad = sin(ds+u * TAU / 20) * M_PI / S7;
+    ld rad;
+    if(vid.flasheffects)
+      rad = sin(ds+u * TAU / 20) * M_PI / S7;
+    else
+      rad = sin((ds+u) * TAU / 20) * M_PI / S7;
     shiftmatrix V1 = chei(V, u, 20);
     queueline(V1*xspinpush0(M_PI+hdir+rad, cgi.hexf*.5), V1*xspinpush0(M_PI+hdir+rad, cgi.hexf*3), col, 2 + vid.linequality);
     }
diff --git a/help.cpp b/help.cpp
index 509caca9..5bf1f953 100644
--- a/help.cpp
+++ b/help.cpp
@@ -1030,7 +1030,7 @@ EX void describeMouseover() {
       }
     #endif
       
-    if(c->wall && !(c->wall == waChasm && c->land == laDual && ctof(c)) &&
+    if(c->wall && !(c->land == laDual && pseudohept(c)) &&
       !(c->land == laMemory) &&
       !((c->wall == waFloorA || c->wall == waFloorB) && c->item)) { 
 
diff --git a/orbs.cpp b/orbs.cpp
index 56ef8a56..a8074fae 100644
--- a/orbs.cpp
+++ b/orbs.cpp
@@ -865,9 +865,11 @@ void telekinesis(cell *dest) {
   eItem it = cwt.at->item;
   bool saf = it == itOrbSafety;
   collectItem(cwt.at, cwt.at, true);
-  if(cwt.at->item == it)
+  if(saf)
+    ;
+  else if(cwt.at->item == it)
     animateMovement(match(dest, cwt.at), LAYER_BOAT);
-  else if(!saf)
+  else
     animate_item_throw(dest, cwt.at, it);
 
   useupOrb(itOrbSpace, cost.first);
diff --git a/passable.cpp b/passable.cpp
index 6dc335d3..e584ad38 100644
--- a/passable.cpp
+++ b/passable.cpp
@@ -143,6 +143,8 @@ EX bool anti_alchemy(cell *w, cell *from) {
 EX bool passable(cell *w, cell *from, flagtype flags) {
   bool vrevdir = bool(flags&P_VOID);
 
+  if(w->land == laDual && pseudohept(w) && !F(P_BULLET)) return false;
+
   if(from && from != w && nonAdjacent(from, w) && !F(P_IGNORE37 | P_BULLET)) return false;
   
   if((isWateryOrBoat(w) || w->wall == waShallow) && F(P_WATERCURSE))
@@ -169,7 +171,6 @@ EX bool passable(cell *w, cell *from, flagtype flags) {
     if(airdist(w) < 3) return false;
     if(againstWind(w,from)) return false;
     if(isGravityLand(w)) return false;
-    if(w->wall == waChasm && w->land == laDual) return false;
     }
 
   if(from && strictlyAgainstGravity(w, from, vrevdir, flags)
diff --git a/pcmove.cpp b/pcmove.cpp
index 345a035d..476623ce 100644
--- a/pcmove.cpp
+++ b/pcmove.cpp
@@ -1143,7 +1143,7 @@ void pcmove::tell_why_impassable() {
     if(vmsg(miRESTRICTED, siGRAVITY, c2, moNone))
       addMessage(XLAT("Gravity does not allow this!"));
     }
-  else if(c2->wall == waChasm && c2->land == laDual) {
+  else if(c2->land == laDual && pseudohept(c2)) {
     if(vmsg(miRESTRICTED, siWALL, c2, moNone))
       addMessage(XLAT("You cannot move there!"));
     }
diff --git a/rogueviz/presentation.cpp b/rogueviz/presentation.cpp
index 3638e94c..34a107bf 100644
--- a/rogueviz/presentation.cpp
+++ b/rogueviz/presentation.cpp
@@ -208,7 +208,8 @@ string latex_cachename(string s, flagtype flags) {
   return hr::format("latex-cache/%08X.png", hash);
   }
 
-/* note: you pdftopng from the xpdf package for this to work! */
+/* note: for this to work, you need either pdftopng from the xpdf package,
+ * or pdftoppm from the poppler-utils package */
 string gen_latex(presmode mode, string s, int res, flagtype flags) {
   string filename = latex_cachename(s, flags);
   if(mode == pmStartAll) {
@@ -225,13 +226,15 @@ string gen_latex(presmode mode, string s, int res, flagtype flags) {
         "\\end{document}\n", latex_packages.c_str(), s.c_str());
       fclose(f);
       hr::ignore(system("cd latex-cache; pdflatex rogueviz-latex.tex"));
+      bool has_working_pdftopng = system("pdftopng -v > /dev/null 2>&1") == 0;
+      string pdftopng_command = has_working_pdftopng ? "pdftopng" : "pdftoppm -png";
       string pngline = 
-        (flags & LATEX_COLOR) ? 
-          "cd latex-cache; pdftopng -alpha -r " + its(res) + " rogueviz-latex.pdf t"
-        : "cd latex-cache; pdftopng -r " + its(res) + " rogueviz-latex.pdf t";
+        (flags & LATEX_COLOR) && has_working_pdftopng ?
+          "cd latex-cache; " + pdftopng_command + " -alpha -r " + its(res) + " rogueviz-latex.pdf t"
+        : "cd latex-cache; " + pdftopng_command + " -r " + its(res) + " rogueviz-latex.pdf t";
       println(hlog, "calling: ", pngline);
       hr::ignore(system(pngline.c_str()));
-      rename("latex-cache/t-000001.png", filename.c_str());
+      rename(has_working_pdftopng ? "latex-cache/t-000001.png" : "latex-cache/t-1.png", filename.c_str());
       }
     }
   return filename;